An assessment on co-combustion characteristics of Chinese lignite and eucalyptus bark with TG–MS technique

Abstract

Reactivity of lignite could be potentially improved by adding with biomass such as lowering the gaseous pollutant emissions. The combustion behavior of lignite/eucalyptus bark blends and their individuals were studied by simultaneous TG–MS technique. The influences of heating rates and blending ratios on combustion performances and gaseous pollutant emissions were assessed. The combustion kinetics were also evaluated in conjunction with volatile matter and fixed carbon burning periods. The ignition and comprehensive combustion indices increased with increasing blending ratios or heating rates. Adding the eucalyptus bark to the lignite was an effective way in reducing the CO2, NO2 and SO2 emissions. The dominant mechanisms associated with combustion kinetics of volatile matters and char in the eucalyptus bark and most eucalyptus bark/lignite blends around maximum burning rates were mainly dominated by the three dimension diffusion, while the combustion mechanisms of char in the lignite were mainly described by reaction order models. Blending ratios of 20–40% eucalyptus bark were proposed as optimum values for improving the combustion behavior of the lignite. There were certain synergistic effects between lignite and eucalyptus bark during their co-combustion.